This week is peak season for Christmas cards, and if you get one that features friends or relatives holding a sign that says “Equality for ALL Families in 2012” or “Love Makes a Family,” you can thank Zach Wahls.

Wahls is an Eagle Scout and engineering student at the University of Iowa, who also happens to be the son of two lesbian moms. Earlier this year, he unleashed an impassioned defense of gay marriage during a public hearing on an amendment in Iowa that would have revoked the state’s residents’ right to marry someone of the same sex, which has been legal in Iowa since 2009.

His speech went viral months ago, garnering Wahls so much attention that he’s now hunkered down writing a book about his experiences called “My Two Moms.” His agent apologized on his behalf that he was too busy writing to speak with Healthland. He did, however, take some time out to craft an email pitch for MoveOn.org urging recipients to incorporate a little politics into their holiday greetings. According to a message signed by Wahls and distributed to millions of MoveOn supporters:

The folks at MoveOn and I had an idea: get as many people as possible to take their family holiday photos holding signs that say ‘Love Makes a Family,’ and ‘Equality for ALL Families in 2012′. This time of year is all about family, so let’s use our holiday photos to send a message of love for ALL families. …

While we won the battle in Iowa, my moms’ rights as a married couple stop at our state’s border. And I know that hundreds of thousands of other families like mine aren’t lucky enough to live in a state where their parents can be married. Instead, they have to spend thousands of dollars to adopt their own kids and get power of attorney to take care of everyday life if or when something bad happens.

A lot of people out there just don’t know and haven’t met families like mine. … Now I’m asking you and other folks to show the people you love that you believe in equality for all.

So far, hundreds of people have uploaded photos — gay families, straight families, old and young, wedding portraits, even one woman holding a photo of her presumably deployed soldier-husband and a sign that reads: “Love makes a family (even from far, far away).”

MoveOn.org recirculated Wahls’ video earlier this month under the memorable heading, “Two Lesbians Raised A Baby And This Is What They Got.” Justin Ruben, executive director of MoveOn, could sense the time was right this holiday season to revive it. “It immediately struck a chord,” says Ruben. More than 20 million people have watched the incredibly eloquent and poised 20-year-old Wahls recount what he says is a common classroom discussion on same-sex marriage. “The question always comes down to, well, Can gays even raise kids?,” says Wahls in the video. “The conversation gets quiet for a moment because most people don’t really have an answer. And then I raise my hand and say, Actually I was raised by a gay couple, and I’m doing pretty well.”

In fact, most research has concluded that children in gay households grow up much like children in other families in many areas including friendships, behavior in school and psychiatric problems, says Charlotte J. Patterson, a professor of psychology at the University of Virginia who studies sexual orientation and family life. They develop similarly to other children in families that share the same socioeconomic background.

One study published in Pediatrics in 2010 found that children in lesbian homes do even better than kids from straight families, scoring higher on some psychological measures of self-esteem and confidence, doing better in school and having fewer behavioral problems like rule-breaking and aggression.

Studies that have focused on “gendered behavior” have found that boys in gay families want to play with the same kinds of toys as boys in heterosexual families. “They are just as likely to pick the trucks and baseballs as other boys,” says Patterson.

Typically, the differences between gay and straight families revolve around the attitudes of others. While children in gay families are not more likely to be bullied than other children, if they are picked on, it’s more apt to be related to their parents’ sexual identities.

In a Reddit chat on Nov. 30, Wahls made a reference to bullying, indicating he was motivated to address the Iowa legislature after a “string of suicides by gay and lesbian kids.”

That impetus only gives Wahls’ message greater urgency. “It felt like this has the potential to move the debate about equality another step forward because it’s not just about marriage,” says Ruben. “It’s about family. It’s a pretty high bar asking people to include something political in their holiday cards, but for anyone who did it, it would be chance to spark more conversation.”

Bonnie Rochman is a reporter at TIME. Find her on Twitter at @brochman. You can also continue the discussion on TIME‘s Facebook page and on Twitter at @TIME.